A significant process in metalworking is the tandem rolling of a metal strip. The rolling process may be classified according to the temperature of the metal being rolled. If the temperature of the metal is above its recrystallization temperature, the process is generally referred to as hot rolling. If the temperature of the metal is below its recrystallization temperature, the process is generally referred to as cold rolling.
The rolling of a hot metal strip presents substantial control challenges due to the complex interaction of a large number of variables, and may involve many non-linear, time-varying variables. This challenge is heightened by the hostile nature of a hot rolling environment, which, for example, may preclude reliably measuring certain variables that may be needed for control purposes.
Known control strategies tend to result in sub-optimal control since often such strategies shy away from systematically addressing the complex dynamic interactions among the large number of variables of the entire rolling mill and their resulting effect on important process variables, such as strip tension, looper position, strip thickness. A few attempts have been made at considering the entire mill as a single entity, e.g., using advanced control techniques based on linearized models, but often these control techniques introduce unacceptable complexities in a real-world setting, such as lack of user-friendliness in connection with the operation and/or tuning of the concomitant controller. Accordingly, there is a need for an improved system to control rolling of a hot metal strip in a rolling mill.